Pallet truck

Abstract

 The present invention relates to a pallet truck (2), comprising a chassis (4), a drive motor (3) and a gear box (5) arranged in the chassis (4) of the pallet truck (2), a drive wheel (7), wherein the drive motor (3) is arranged to transmit power to the drive wheel (7) via the gear box (5) for driving of the pallet truck (2), a tiller arm (6) to be manoeuvred by hand by an operator for adjusting the direction of travel of the pallet truck (2), wherein the drive motor (3) is fixedly arranged in the chassis (4), the gear box (5) and the drive wheel (3) are interconnected and pivotally arranged in the chassis (4), and the tiller arm (6) is connected to the gear box (5) in such a way that the gear box (5) and the drive wheel (7) together are pivoted when the operator manoeuvres the tiller arm (6).

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a pallet truck according to the preamble of claim 1.

BACKGROUND OF THE INVENTION

[0002] For pallet trucks the direction of travel is normally controlled by an operator by manoeuvring a tiller arm, which pivots the drive wheel and thereby changes the direction of travel. When the pallet truck is electrically driven, a drive motor transmits power to the drive wheel via a gear box containing a gear mechanism.

[0003] A prior art solution is to assemble the drive motor, the gear box and the drive wheel together on top of each other and make the whole drive assembly pivotal with respect to the chassis of the pallet truck. The tiller arm is then attached to the drive motor at a point on top of the drive motor, and when the operator manoeuvres the tiller arm the whole drive assembly is pivoted. The electrical drive motor is supplied with power from e.g. a battery pack by means of electrical cables. Thus, the electrical cables must be of excessive lengths to allow the drive assembly to be pivoted.

[0004] However, excessive lengths of electrical cables are bulky and require a lot of space. Moreover, when the drive motor is pivoted the electrical cables are bent which may cause operational disturbances.

[0005] Moreover, the tiller arm attachment point at the top of the drive motor has to be strong enough to hold and transfer the momentum created through the steering force exerted on the tiller arm. Therefore, the top of the drive motor has to be adapted for this purpose, which makes the drive motor more expensive.

OBJECT OF THE INVENTION

[0006] An object of the present invention is to provide a pallet truck with a less bulky electrical cabling.

[0007] Yet an object of the present invention is to minimise operational disturbances in a pallet truck due to bending of electrical cables.

SUMMARY OF THE INVENTION

[0008] These objects of the invention are achieved by means of a pallet truck as initially defined and having features according to the characterising portion of claim 1.

[0009] Since the drive motor is fixedly arranged in the chassis, the gear box and the drive wheel are interconnected and pivotally arranged in the chassis, and the tiller arm is connected to the gear box in such a way that the gear box and the drive wheel together are pivoted when the operator manoeuvres the tiller arm, several advantages are achieved. Firstly, the lengths of the electrical cables which supply the drive motor with power do not have to be excessive, since the drive motor is fixed and stationary with respect to the chassis and therefore do not need to compensate for any pivot motions as in related art solutions. Thus, a less bulky electrical cabling is achieved. Secondly, the electrical cables will for the same reasons not be subjected to bending when the direction of travel of the pallet truck is adjusted. Thus, the risk of operational disturbances is minimised.

[0010] Preferably, the tiller arm is attached to the gear box via a tiller arm bracket, which is mounted to the gear box. Hereby the tiller arm can be easily mounted to the gear box, and the top of the drive motor need not be adapted so it becomes strong enough to hold and transfer the momentum created through the steering force exerted on the tiller arm.

[0011] Suitably, the drive motor is arranged on top of the gear box and the tiller arm bracket comprises a first portion which extends upwards along the side of the drive motor. Hereby a plurality of conceivable fastening points for the tiller arm is achieved along the first portion.

[0012] Preferably, the first portion is radially separated from the drive motor to avoid interference with the drive motor, when the gear box and the drive wheel are pivoted.

[0013] Suitably, the tiller arm bracket comprises a second portion which is connected to the first portion and which extends radially inwards on top of the drive motor. Hereby an attachment point for the tiller arm is achieved which facilitates casing of the drive motor and the gear box.

[0014] Preferably, the second portion comprises a recess for attachment of the tiller arm, and wherein the position of the recess coincides with the motor axis of the drive motor. Thus when the tiller arm is attached at the recess, the size of the opening in the casing need only be as large as it allows the tiller arm to be lead through, since no compensation has to be made for the pivot motion itself.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will now be described with reference to accompanying drawings, on which:

Fig. 1 shows a schematic side view of an electrically driven pallet truck comprising a drive assembly according to the present invention.

Fig. 2 shows a perspective view of the drive assembly in fig. 1.

Fig. 3 shows a side view of the drive assembly in fig. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0016] Fig. 1 shows a perspective view of an electrically driven pallet truck 2. The pallet truck comprises a chassis 4 which is supported on the ground by means of front wheels 8 and a rear rotary drive wheel 7. The drive wheel 7 can be pivoted by means of a tiller arm 6, which is manoeuvred by the operator of the pallet truck 2, for adjusting the direction of travel of the pallet truck 2.

[0017] Fig. 2 is a perspective view of a drive assembly 1 for the pallet truck shown in fig. 1. The drive assembly 1 comprises an electrical drive motor 3, a gear box 5 and the rotary drive wheel 7, wherein the electrical drive motor 3 is intended to transmit power to the drive wheel 7 via the gear box 5 for driving of the pallet truck. The electrical drive motor 3 rests in a fastening device 9, which is to be fixedly attached to the chassis 4 of the pallet truck 2 by means of not shown bolts (see holes 11 intended for the bolts). The electrical drive motor 3 is moreover secured in the fastening device 9 by means of screws 13 so that it is fixed and stationary with respect to the chassis 4.

[0018] Fig. 3 shows the gear box 5 being attached to the electrical drive motor 3 below the fastening device 9. Between the electrical drive motor 3 and the gear box 5 a guide bearing 15 is arranged so as to allow the gear box 5 to pivot with respect to the electrical drive motor 3, and thus with respect to the chassis 4. The gear box 5 can pivot about a vertical axis 17 which coincides with the motor axis of the electrical drive motor 3.

[0019] The gear box 3 comprises a not shown gear mechanism to which the rotary drive wheel 7 is connected to achieve a desired gear ratio. Since the drive wheel 7 is connected to the gear box 5, which is pivotal with respect to the chassis 4 of the pallet truck 2, the drive wheel 7 and the gear box 5 will together pivot about the vertical axis 17. The drive wheel 7 is arranged in the rear end of the pallet truck and rests on the ground so as to support the weight of the pallet truck (together with the front wheels 8). By pivoting the drive wheel 7 (and additional castor wheels on both sides of the drive-wheel (7) if necessary), the direction of travel of the pallet truck can be adjusted.
For pivoting the drive wheel 7 the tiller arm 6 is employed and which is to be manoeuvred by an operator of the pallet truck 2. The tiller arm 6 is attached to an attachment portion 19 forming part of the gear box 5, by means of an elongated tiller arm bracket 21. The tiller arm bracket 21 is attached to the attachment portion 19 by means of a screw joint comprising three socket head cap screws 23. The tiller arm bracket 21 comprises a first portion 25 which extends vertically upwards along, and radially separated from, the electrical drive motor 3 and terminates in a bent second portion 27 being located above, and axially separated from, the electrical drive motor 3. The position of the recess 29 is located so it coincides with the motor axis 17 of the drive motor 3. The second portion 27 comprises a recess 29 to which the tiller arm is to be attached. By proving the tiller arm bracket 21 with such a second portions 27 the drive assembly 1 can be easily enclosed by a not shown shell having an opening for the tiller arm on top of it.

[0020] Alternatively, the tiller arm can be attached to the tiller arm bracket 21 at an arbitrary point along the first portion 25, which provides a more flexible choice of vertical attachment points of the tiller arm 6.

[0021] Accordingly, when the tiller arm is manoeuvred by the operator, the gear box 5 and the drive wheel 7 is pivoted together, while the electrical drive 3 motor is stationary. Hereby the direction of travel of the pallet truck can be adjusted. With this solution, i.e. with a stationary electrical drive motor 3 and with the tiller arm 6 being attached directly to the gear box 5, the length of the electrical cables which supplies the electrical drive motor 3 with power from a battery pack, need not be excessive. Moreover the electrical cables will not be subjected to bending and therefore operational disturbances will not occur. Additionally the top of the drive motor need not be adapted so it becomes strong enough to hold and transfer the momentum created through the steering force exerted on the tiller arm.

Claims

1. Pallet truck (2), comprising:

- a chassis (4),

- a drive motor (3) and a gear box (5) arranged in the chassis (4) of the pallet truck (2),

- a drive wheel (7), wherein the drive motor (3) is arranged to transmit power to the drive wheel (7) via the gear box (5) for driving of the pallet truck (2),

- a tiller arm (6) to be manoeuvred by hand by an operator for adjusting the direction of travel of the pallet truck (2),

characterised in that the drive motor (3) is fixedly arranged in the chassis (4), the gear box (5) and the drive wheel (3) are interconnected and pivotally arranged in the chassis (4), and the tiller arm (6) is connected to the gear box (5) in such a way that the gear box (5) and the drive wheel (7) together are pivoted when the operator manoeuvres the tiller arm (6).

2. Pallet truck (2) according to claim 1, wherein the tiller arm (6) is attached to the gear box (5) via a tiller arm bracket (21), which is mounted to the gear box.

3. Pallet truck (2) according to claim 2, wherein the drive motor (3) is arranged on top of the gear box (5), and the tiller arm bracket (21) comprises a first portion (25) which extends upwards along the side of the drive motor (3).

4. Pallet truck (2) according to claim 3, wherein the first portion (25) is radially separated from the drive motor (3) to avoid interference with the drive motor (3) when the gear box (5) and the drive wheel (7) are pivoted.

5. Pallet truck (2) according to claim 3 or 4, wherein the tiller arm bracket (21) comprises a second portion (27) which is connected to the first portion (25) and which extends radially inwards on top of the drive motor (3).

6. Pallet truck (2) according to claim 5, wherein the second portion comprises a recess (29) for attachment of the tiller arm, and wherein the position of the recess coincides with the motor axis (17) of the drive motor (3).

Drawing